1. Field of the Invention
The present invention relates to systems and methods for the transmission of messages between at least one mobile station and another network without requiring connection to a controller of a wireless system containing the at least one mobile station.
2. Description of the Prior Art
FIG. 1 illustrates a diagram of a prior art system 10 and method in accordance with the Third Generation Partnership Project (3GPP) for providing multicast services. The system 10 includes a wireless network 12 which is comprised of a plurality of mobile stations 14 (only one is illustrated), a plurality of base stations 16 (only one is illustrated), and a radio network controller 18 which controls the use and integrity of the radio resources of the wireless network 12. An external network 20, which is independent of the wireless network 12 and is either a source of multicast transmissions to the plurality of mobile stations or acts as an intermediate network domain between a source of the multicast transmissions and the mobile station 14, is connected to the wireless network. Multicast transmissions originated from the external network 20 or from another network connected thereto are transmitted by the wireless network 12 to the plurality of mobile stations 14 which allow the users who control the mobile stations to receive a common and simultaneous wireless transmission through the air interface of the wireless network from base stations 16 to the mobile stations.
Broadcast and multicast transmissions are well known. Broadcast transmissions are sent to mobile stations, whose identification and location are unknown as the result of, for example, no joining procedure having been completed. Multicast transmissions, on the other hand, are transmitted to only those subscribers that have previously indicated an interest in receiving the multicast service from the network, who can be identified after performance of the multicast joining procedure or whose location can be determined by tracking procedures.
In order to establish if subscribers or users, who control the mobile stations 14, are willing to receive a service providing a multicast or restricted broadcast transmission, two phases are executed. The first phase is the service registration phase during which subscribers or users, who possess the mobile stations 14, agree with the a service provider or operator who controls the core network 20 or the external network connected thereto, to receive the multicast or restricted broadcast services. The second phase is the multicast joining or subscription phase during which the subscribers or users, who possess the mobile stations 14, indicate a willingness to the service provider to receive the multicast or restricted broadcast services in order to obtain currently defined service configuration parameters of the multicast or restricted broadcast services. If the current service parameters have already been given to the mobile stations 14 during the registration phase, the user of the mobile stations indicates a readiness to receive multicast or restricted broadcast services which enables the wireless network 12 and the external network 20 to make routing and resource management decisions which involve point to multipoint connections, such as a connection between the core network and the mobile stations regarding the offered service.
The most significant event of the above-described registration and multicast joining or subscription phase is the indication by the subscriber or user of the mobile stations 14 of a willingness to receive an ordered multicast or restricted broadcast service from the service provider controlling the external network 20 or network connected thereto. Subscription, which is required for the broadcast services (i.e. broadcast service, which are meant only to a restricted group of people), is always non time critical (i.e. it can be made e.g. hours before the reception of the broadcast service, whereas the joining phase can be time critical (i.e., it is made just before the multicast transmission of the particular service is started) or a nontime-critical transaction (i.e., the joining phase can be completed before the actual service activation). Depending on whether the joining transaction is a time-critical or a nontime-critical transaction, services involving different subscriber service charges can be defined for the multicast or restricted broadcast service. This is a significant aspect of providing multicast or restricted broadcast services.
In accordance with the 3GPP specifications, the execution of the above-described joining or subscription phase to obtain multicast or restricted broadcast transmissions requires that the wireless network have available uplink radio resources for the joining or subscription phase. As indicated in FIG. 1, when the mobile stations are in a radio resource control idle state 21 (defined in the 3GGP specifications as the state of user equipment being switched on, but not having an established termination to the controller of the wireless system), a radio resource control request 22 is transmitted from at least one mobile station 14 to the radio network controller 18. Under the 3GGP specifications, the only uplink radio resources available for the mobile stations in IDLE state 21 are the Physical Random Access Channel (PRACH) on the air interface and the Random Access Channel (RACH) as a transport channel, which channels, unfortunately, have other usages than completing the multicast joining or subscription phase necessary to obtain multicast or broadcast services. The PRACH and the RACH channels also transmit dedicated signaling messages related to the use of the mobile stations 14 and also permit transmission of small amounts of data on the user plane as defined in the 3GGP specifications. As a result, the transmission of multicast joining or subscription messages through the aforementioned PRACH and RACH channels between the mobile stations 14 and the radio network controller 18 can substantially utilize the capacity of these radio resources making these radio resources unavailable for other types of transmissions.
As illustrated in FIG. 1, after the transmission of the RRC connection request 22 to the radio network controller 18, a RRC Connection Setup Procedure 24 is completed to establish the aforementioned RRC connection (i.e. for the mobile stations 14, the radio network controller 18 creates the RRC context). Thereafter, the mobile stations 14 enter into a RRC Connected state (i.e. Cell_FACH or Cell_DCH state). Depending on which state the mobile stations 14 are ordered to enter, the radio network controller 18 reserves for the mobile stations either a dedicated channel DCH or the mobile stations are allowed to use a Forward Access Channel (FACH) in the downlink and a Random Access Channel (RACH) in the uplink as indicated at point 26. Finally, the actual transmission of the multicast or broadcast related signaling information transmission from the core network 20 to the at least one mobile station 14 occurs over the aforementioned channels established at point 26 as indicated by point 28.
Furthermore, an additional problem exists resultant from the transmission of the multicast joining or subscription messages. Multicast joining or subscription messages are, in accordance with the 3GGP specifications, “Non-Access Stratum” (NAS) messages which require an existing RRC connection as indicated at point 24. Since a high probability exists that most of the mobile stations 14 are in the idle state 21, the establishment of the RRC connection 24 for the only purpose of the multicast joining or subscription messages to most often obtain a later accessibility to multicast or broadcast services from the core network 20 can be a significant load on the wireless network 12. This load can decrease or interfere with access to the multicast transmissions from the core network 20 to the mobile stations 14. This interference is especially significant if a multicast joining phase is time-critical in view of the service agreement between the core network 20 and the subscribers of the at least one mobile station 12.